000
FXUS62 KRAH 311852
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
252 PM EDT FRI JUL 31 2015
.SYNOPSIS...A COLD FRONT WILL STALL OVER SOUTHEAST NORTH CAROLINA
THIS AFTERNOON...AND LINGER IN THIS REGION THROUGH THE WEEKEND. WEAK
HIGH PRESSURE WILL BUILD INTO THE PIEDMONT AND PERSIST THROUGH THE
WEEKEND.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
AS OF 1015 AM FRIDAY...
MAIN ADJUSTMENT IN THE NEAR TERM FORECAST WAS TO DWINDLE PRECIP
CHANCES A BIT OVER THE SE COUNTIES.
12Z UPPER AIR ANALYSIS DEPICTS A DRIER SLIGHTLY MORE STABLEAIR MASS
FILTERING INTO CENTRAL NC. ANTI-CYCLONIC FLOW NOTED OVER THE BULK OF
THE REGION AT 925-850MB WHILE MOISTURE BECOMING LIMITED BELOW 600MB.
PER MESO ANALYSIS...APPEARS ENOUGH RESIDUAL MOISTURE WILL EXITS
ALONG A WILSON-LAURINBURG LINE SOUTHWARD TO RETAIN A SLIGHT-SMALL
CHANCE POP LATER THIS AFTERNOON-EARLY EVENING. FARTHER NORTH AND
WEST...ATMOSPHERE APPEARS TOO DRY AND FORCING LIMITED TO HEATING SO
A POP LESS THAN 20 PERCENT SHOULD SUFFICE.
SLIGHTLY WARMER THAN PREDICTED TEMPS AT 850MB SUPPORT THE FORECAST
OF AFTERNOON TEMPS IN THE 90-95 DEGREE RANGE. ACROSS MOST OF THE
PIEDMONT...LOW LEVEL NLYFLOW WILL ADVECT A DRIER DEWPOINTS WITH MID
AFTERNOON DEWPOINTS IN THE UPPER 50S TO AROUND 60 HIGHLY PROBABLE.
THUS...IT WILL FEEL LESS HUMID (AND THE HEAT SLIGHTLY MORE
TOLERABLE) COMPARED TO THE PAST FEW DAYS.
TONIGHT...ANY LINGERING CONVECTION OVER THE SE COUNTIES SHOULD
DIMINISH SHORTLY AFTER SUNSET. RESIDUAL LOW LEVEL MOISTURE MAY LEAD
TO PATCHES OF LIGHT FOG IN VICINITY OF KFAY...KGSB...AND KCTZ BY
EARLY SATURDAY. ELSEWHERE EXPECT FAIR-PARTLY CLOUDY SKIES. MIN TEMPS
LOW-MID 60S NW TO LOWER 70S SE. -WSS
SAT/SAT NIGHT: A QUIET DAY AS THE MEANTROUGH AXIS HOLDS OVERHEAD...
WITH THE SURFACE FRONTAL ZONE STRETCHING THROUGH ERN AND SE NC AS
HIGH PRESSURE BUILDS IN FROM THE WNW. EXPECT A ROUND OF ISOLATED MID-
LATE AFTERNOON SHOWERS AND STORMS OVER THE FAR SE WITHIN MARGINAL
INSTABILITY AND WEAK LOW LEVEL MASS CONVERGENCE... WITH DRY WEATHER
ELSEWHERE GIVEN THE DRY AND SUBSIDING MID LEVELS AND FALLING PW
VALUES. AGAIN LEANING TOWARD A DRY ADIABATIC LOW LEVEL LAPSE RATE...
EXPECT HIGHS OF 90-95... WITH LOWS SAT NIGHT 63-70. -GIH
&&
.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 200 AM FRIDAY...
A STAGNANT UPPER LEVEL PATTERN WILL REMAIN IN PLACE ON SUNDAY AND
MONDAY WITH A SLIGHTLY DEEPENINGUPPER LEVELTROUGH OVER THE EASTERN
CONUS AND NEAR STATIONARY RIDGE OVER THE SOUTHWESTERN UNITED STATES.
DURING THIS PERIOD A WEAK SURFACE HIGH OVER THE OHIO VALLEY WILL
KEEP CONDITIONS RELATIVELY DRY. TO THE NORTH...A LOW PRESSURE SYSTEM
NORTH OF THE GREAT LAKES WITH AN ASSOCIATED FRONTAL SYSTEM
STRETCHING SOUTHWARD...WILL IMPINGE UPON THE SURFACE HIGH BY THE END
OF THE SHORT TERM... HELPING TO WEAKEN THE HIGH BUT SHOULD STILL
REMAIN DRY IN THE NORTHWEST PIEDMONT. THE ONLY CHANCE FOR
PRECIPITATION WILL COME IN THE FORM OF POTENTIAL DIURNALCONVECTION...PARTICULARLY IN THE FAR SOUTHEAST WHERE RETURN FLOW
AROUND THE BERMUDA HIGH WILL BRING INCREASED MOISTURE INTO THE AREA
WHICH COULD USE THE SEA BREEZEFRONT AS A CATALYST FOR CONVECTION
DURING THE AFTERNOON/EARLY EVENING HOURS. REGARDLESS...THE AIRMASS
AS A WHOLE WILL BE VERY DRY FOR THIS TIME OF YEAR WHICH WILL KEEP
PRECIP CHANCES VERY LOW. HIGH TEMPERATURES WILL BE IN THE LOWER 90S
WITH LOWS IN THE UPPER 60S NW TO LOW 70S SE. DEWPOINTS WILL MODERATE
FROM THE LOWER 60S ON SUNDAY TO MID TO UPPER 60S BY
MONDAY...RESULTING IN AND OVERALL INCREASE IN HUMIDITY.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 245 PM FRIDAY...
THE LATEST 12Z MODEL GUIDANCE IS IN RELATIVELY GOOD AGREEMENT
W/REGARD TO THE EVOLUTION OF THE UPPER LEVEL PATTERN NEXT WEEK. THE
DEEP UPPER LEVELRIDGE CURRENTLY CENTERED OVER THE WESTERN CONUS
/INTERMOUNTAIN WEST/ WILL GRADUALLY SHIFT EASTWARD TO THE ROCKIES BY
THE MIDDLE OF NEXT WEEK...AND AS THE RIDGE AXIS SHIFTS EAST...A MORE
ACTIVE /ENERGETIC/ PATTERN OF NORTHWEST FLOW ALOFT WILL DEVELOP
DOWNSTREAM OVER THE OH VALLEY/MID-ATLANTIC. FROM A PATTERN
RECOGNITION STANDPOINT...ONE WOULD EXPECT ABOVE NORMAL TEMPERATURES
(MID 90S) AND BELOW NORMAL CHANCES FOR CONVECTION TO PERSIST THROUGH
EARLY NEXT WEEK...TRANSITIONING TO NEAR NORMAL TEMPERATURES AND
AT/ABOVE NORMAL CHANCES FOR CONVECTION BY MID/LATE NEXT WEEK. GIVEN
THAT ENHANCED CONVECTIVE COVERAGE/TIMING WILL BE HIGHLY SENSITIVE TO
THE PRECISE EVOLUTION OF SMALL AMPLITUDE WAVES...UPSTREAMCONVECTION
(I.E. MCS ACTIVITY)...AND/OR CONVECTIVE REMNANTS (I.E. OUTFLOW/
MCV`S)...IT IS DIFFICULT IF NOT IMPOSSIBLE TO DETERMINE FORECAST
SPECIFICS (CONVECTIVE TIMING/COVERAGE/INTENSITY) MID TO LATE NEXT
WEEK. GIVEN THAT STRONGER DEEP LAYER SHEAR AND STEEPER MID-LEVEL
LAPSE RATES (I.E. MODIFIED EML) ARE MORE LIKELY TO BE PRESENT IN A
SYNOPTIC PATTERN CHARACTERIZED BY NW FLOW ALOFT...AN ENHANCED
POTENTIAL FOR SEVERE THUNDERSTORMS MAY BE PRESENT AT SOME POINT IN
THE WED-FRI TIME FRAME...PRIMARILY IF DIURNAL TIMING IS FAVORABLE
W/REGARD TO APPROACHING SHORTWAVE ENERGY. -VINCENT
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 145 PM FRIDAY...
THERE IS HIGH CONFIDENCE THAT VFR CONDITIONS WILL PERSIST ACROSS
CENTRAL NC THROUGH 12Z SUNDAY. THE EXCEPTION WILL BE A BRIEF
INSTANCE OF MVFRVISIBILITY DUE TO FOG EARLY SATURDAY MORNING IN
VICINITY OF KFAY. OTHERWISE SURFACE WINDS WILL BE LIGHT AND VARIABLE.
VFR CONDITIONS WILL PREVAIL THROUGH MOST OF THE UPCOMING WEEK. THERE
WILL BE AN INCREASE IN THE POTENTIAL FOR EARLY MORNING FOG AND LOW
CLOUDS AS THE LOWER LEVELS OF THE ATMOSPHERE BECOME INCREASINGLY
MOIST...AS WELL AS A THREAT FOR SCATTEREDCONVECTION IN THE
AFTERNOON AND EARLY EVENING HOURS...ESPECIALLY BEYOND MONDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...WSS/HARTFIELD
SHORT TERM...ELLIS
LONG TERM...VINCENT
AVIATION...WSS